DE2756976A1 - COAL LIQUIDATION PROCEDURE - Google Patents

Description

Our no. 21 188

Chevron Research Company 27 569 76

San Francisco, CaI., V. St. A.

Coal liquefaction process

The invention relates to a coal liquefaction process, in which the normally liquid product has a low sulfur and nitrogen content and a particularly high one Has all-density.

As a result of the increasing price and the lower availability of petroleum, research is striving lately afterwards, new possibilities of synthetic fuel production found from solids such as coal. In addition, because of the increasing importance that prevention exists Given environmental pollution, there is a great need for fuels with low levels of sulfur and nitrogen held. The disadvantage here is that most types of coal contain large amounts of sulfur and nitrogen, which eventually reappear in the synthetic, coal-derived fluids, creating additional and costly steps must be taken to remove the sulfur and nitrogen therefrom, which in turn leads to an increase in the price of fuel.

A number of coal liquefaction processes are known. In many such processes, hydrogen is used supplied by a hydrogen donating solvent. The function of the catalyst is in this process in combining the solvent with hydrogen again by adding molecular hydrogen. Consequently the solvent serves as the medium, the hydrogen from the catalyst to carry solid coal. However, the catalyst is usually quickly deactivated in such processes.

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fourth, with the result that the process is inefficient and is therefore not suitable as an industrial carbohydrate process

Another problem that arises with the known processes arises from the insoluble solids, contained in the liquid product obtained from the coal liquefaction process and have a high molecular weight condition. Due to the high molecular weight, it is difficult to remove the very fine, insoluble solid particles (carbon residues) separated from the product. In addition, there was general doctrine that these insoluble solids should be removed before further processing in order to allow for a subsequent catalyst deactivation to avoid.

ΔΪη further problem in the known coal liquefaction processes is that the normally liquid product typically contains 0.2 to 1.0 or more wt.% Sulfur and otickstoff. These potential contaminants must be removed in order to obtain valuable and clean fuel. Further treatment steps are required to remove the contaminants, which in turn makes the product more expensive.

The catalytic coal liquefaction process disclosed in "Coal Conversion Technology" by Smith et al, N§yes Data Corporation (1976) can be considered a typical process in the art Temperature of 482 ⁰ C

maintained catalyst bed at 140.6 kg / cm above atmospheric pressure pushed through. After publication, the product

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by Sun w. Ohun, National Science Foundation, Ohio State University workshop, in "iaaterials Problems and Research "of April 16, 1974 ·, a density of 1.2 ° .aPI, a sulfur content of 0.11 wt <,; ö and a nitrogen content of 0.63

Rfahren Another known V _e represents the Synthoil method represents, in which a slurry of a coal solvent in a reactor having catalytic fixed bed is pumped, together with hydrogen at a high speed, similar to the GUIF method is also in Synthoil method a according to the The teaching disclosed in "Coal-Liquefaction" by Sam Friedman et al (presented at the NPRA Conference on National Fuels & Lubricants, Nov. 6-8, 1974, in Houston, Texas, USA) created liquid product that an All having density of ^0.72-0 and a sulfur content of 0.2 wt. o}.

It is the object of the invention to propose a further developed process for liquefying coal, by means of which a normally liquid product with an all-density of at least -3, a sulfur content of less than 0.10 wt / β and a less than 0.50 wt. 70 lying nitrogen content is created.

In addition, the invention is intended, in particular, in Turbines usable fuel are created as a normally liquid product of solids free is.

The invention is also intended to create a liquid product from which insoluble carbon solids (cooling bag) are easily

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Can be removed more efficiently and economically, e.g. by separation of gravity.

The liquefaction process proposed by the invention includes:

a) Form a coal dissolving slurry by mixing the finely divided coal with a solvent,

b) largely dissolving the coal in the solvent by heating the slurry to between 399 and 482 ° C lying temperature, which creates a mixture of solvent, dissolved carbon and insoluble solids,

c) bringing the mixture in a reaction zone with hydrogen and a suitable hydrocracking catalyst under conditions favorable to hydrogenolysis at a temperature below 427 ⁰ C temperature is contacted, and

d) branch off the stream leaving the reaction zone, the normally liquid part of which has an API density of has over -3.

)
Also, the normally liquid portion of the product has an extremely low sulfur content of less than 0.10% by weight and a nitrogen content below 0.5% by weight.

There is a special feature that is critical to success in that the process is carried out in at least two separate and individual process stages under critical conditions will. It is essential here that the coal is in a high-temperature first stage in the range from 399 ° to 482 ° C is largely dissolved to form a mixture of dissolved charcoal,

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To give solvent and undissolved solids, and the mixture under suitable for the hydrogenolysis under conditions at a 427 ⁰ C, but is preferably accommodated in the region of 315 »6 lying ° to 426 ⁰ O critical temperature with a Hydrokrackungskatalysator in contact. Preferably the temperature in the hydrocracking stage will always be below the temperature in the dissolving zone, ie by 55 to 83 ° C below.

An exemplary embodiment of the invention is illustrated below of the schematic flow diagram.

In d'e- mixing zone 10, finely divided coal is together with given to a hydrogen donor solvent. The base feed of the invention are divided solid coal particles Anthracite, bituminous coal, bituminous lignite, lignitic lignite and their mixtures. Particularly preferred become bituminous coal and bituminous lignite. In general, it is convenient to reduce the carbon to a particle size from about 100 on the Tyler scale and even smaller to grind. Sizes above this can also be used.

The solvents are known in the art and include aromatic hydrocarbons that are partially hydrogenated and have at least one partially saturated ring or several thereof. examples for this are Tetralin (tetrahydronaphthalene), dihydronaphthalene, dihydroalkylnaphthalene, Dihydrophenanthrene, dihydroanthracene, Dihydrochrysen and the like. These substances can be various Sources, but they are most easily obtained from the product of the invention. Is cheapest es, a solvent obtained from the process, in particular the proportion of the boiling fraction of 204 ° C and above

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809826 ^ 0857

-s-

obtainable from fractionation of the stream discharged from the hydrocracking zone, as further described below.

The coal particles are mixed with a solvent in a weight ratio of solvent to coal of 0.5: 1 to 5: 1, preferably from about 1: 2 to 3: 1, in particular from about 1: 1 to 2: 1. From the mixing zone 10, the slurry passes via line 15 into the solution zone 20, in which it is heated to a temperature of 399 to 482 ° C., preferably to 427 to 454 ° C. and, in the most favorable case, to 438 to 449 ° C. until the coal is largely dissolved. At least 50 percent by weight, better still more than 70 percent and most preferably more than 90 percent of the coal, calculated on a moisture and ashless basis, is dissolved in the zone so that a mixture of solvent, dissolved coal and insoluble solids is formed will. It is essential here that the slurry is ^{heated to at least 399 °} C. in order to achieve at least a 50 percent solution of the coal. But it is also important that the coal is not heated to a temperature above 482 ° C, as this leads to cracking via radicals, which significantly reduces the yield of the normally liquid products.

Preferably, hydrogen, which consists of fresh hydrogen and the cycle gas, is also fed to the solution zone via line 17. With the exception of temperature, the reaction conditions in the dissolution zone can vary widely so that a minimum of at least 50 percent dissolution of the solids is achieved. The other reaction conditions in the solution zone include a residence time of 0.01 to 3 hours, preferably 0.1 to 1.0 hours, in the range of 0 to 703 kg / cm ² ,

809826/0357

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above atmospheric pressure, preferably at 105 to 176 Kg / cm

ο and even better at 105 to 352 kg / cm above atmospheric Pressure, a hydrogen gas velocity from 0 to 566 nr at 15 »6 C per 159 liters of slurry and preferably 85 up to 283 m at 15.6 C per 159 liters of slurry. Will the If hydrogen is added to the solution zone, the pressure in the solution zone should be kept above 36 kg / cm. The elutriation can go up or down in the solution zone stream. The zone should preferably be sufficiently elongated so that conditions (plua flow) be created, under which it is possible to use the method according to the invention continuously and not as a periodic, to operate intermittently operating procedures.

The dissolution zone does not contain any catalyst from an external source, although that is contained in the coal Minerals can have a catalytic effect.

The mixture of dissolved charcoal, solvent and insoluble contaminants is sent to a second reaction stage zone 30 passed, the one suitable for hydrogenative cleavage Has catalyst. In the hydrocracking zone the hydrogenation and the cracking take place simultaneously, with the compounds of higher molecular weight being transformed into such of lower molecular weight, the sulfur compounds in hydrogen sulfide, the nitrogen compounds in ammonia and the oxygen compounds are converted to water. Preferably the catalytic reaction zone is fixed Bed trained; but it could also be an "ebullating" (ebullating) bed can be used. The mixture of gas, liquids and insoluble pesticides goes to the top

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through the catalytic reaction zone; but it can also be led downwards.

The catalysts used in the second stage of the process may be the known commercially available hydrocracking catalysts. A suitable catalyst in this regard comprises a hydrogenation and a cracking component. Preferably, the hydrogenation component is from a refractory carrier Cracking component carried, for example, of two or more oxides such as silica-alumina, silica-magnesium oxide, silica-zirconium oxide, silica-boron trioxide, silica-titanium dioxide, Silica-zirconia-titania, acid-treated fuller's earth, and the like. Acidic metal phosphates, such as Alumina phosphate can also be used. Catalysts are preferably used for hydrocracking, containing a Group VIII metal and an acidic cracking component as a carrier.

The preferred cracking bases contain compositions of silica and alumina. The suitable hydrogenation components are selected from metals of group VI-B, metals of group VIII and their oxides or mixtures. Particularly suitable are cobalt-molybdenum, nickel-molybdenum or nickel-tungsten based on silica-alumina.

It is critical for the process according to the invention not to keep the temperatures in the hydrocracking zone too high, since it has been found that the catalyst is rapidly loaded with carbon at high temperatures. The temperature in the The hydrocracking zone must be below 427 ° C, preferably in the range of 315.6 ° C to J »26 ° C, and more preferably between 3 *» 3 to 399 ° C being held.

In general, the temperature in this zone is always below the temperature prevailing in the solution zone, preferably by 55 to 83 ^° C. lower. Other hydrocracking conditions include a pressure of 35 to 352 Kg / cm

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above atm, preferably 70 to 211 kg / cm above atm, and more preferably between 105 to 14-6 Kg / cm over atm, and a Hydriergescliwindigkoit of 56 »6-566 ° BE * 15.6 ⁰ C per 159 1 slurry, preferably 85 to

⁷ I O

28J nr at 15.6 G per 159 1 ^ slurry, as well as an im Slurry hourly head velocity in the range 0.1 to 2, preferably in the range 0.2 to 0.

Preferably the pressures are in the non-catalytic dissolution stage and the hydrocracking catalytic stage are essentially the same.

Preferably all of the stream discharged from the dissolving zone is directed to the hydrocracking zone. However, since small Lengen water and light gases (C. to C ^) in the first Stage are generated, the catalyst is exposed to a lower hydrogen partial pressure in the second stage as if these substances were not present. As higher, hydrogen partial pressures tend to reduce the life of the To extend catalysts, it can prove to be advantageous in industrial operations, some of the water and of the light gases before the stream enters the hydrocracking stage.

The Produltetrom emerging from the reaction zone 30 is separated into a gas fraction 36 and a solid fraction 37. The gas fraction comprises light oils with a boiling point below about 149 to 26O ⁰ C, preferably less than 204- ⁰ C, and normally gaseous components such as Hp, Co, COQ, HPS and Gi to Cv hydrocarbon It is expedient 'Hp from the other To separate gas components and circulate in the hydrocracking or solution stages as desired

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permit. The solid-liquid fraction 37 becomes the solids separation zone 40 led, where the current in a low in solids stream 55 and in i'estsubstanzen are enough electricity 45 separately. The insoluble ones Solids are removed by conventional means, e.g. Hydrocycloning, filtration, centrifugation and gravity separation, or a combination of such methods separated. The gravity separation is given preference because it therefore offers an additional advantage according to the invention, namely that which emerges from the hydrocracking reaction zone Stream has a particularly low viscosity and a high API density of at least -3. Due to the The exiting stream can be all-density by gravity separation Are quickly separated from the solids, so that 50% by weight and generally 90% by weight of the solids in one Gravity settling tanks are separated. The insoluble ones Solids are conveniently separated by gravity at an elevated temperature in the range from 93 to 427 ° C, preferably The temperature between 149 and 15 ° C is between 0 and 352 kg / cm above atm, preferably between 0

up to 70.3 kg / cm above atmospheric pressure removed. the Solids separation at an elevated temperature and pressure is particularly advantageous. The one on solids poor stream is diverted via line 55 and fed back to the mixing zone, while that is rich in solids Current through line 45 of a secondary solids separation zone 50 is forwarded. In zone 50, methods of distillation, fluid coking, delayed coking, centrifugation, Hydrocloning, filtering, settling or processes combined therefrom are used. the separated solids are via line 52 from the Zone 50 removed and discharged, while the liquid product is discharged via line 5 ^ ·. The liquid $> j? Oflukt is largely freed from solids and contains less than 1.0% by weight.

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Urs erfindiingsgerx.'i. '. El / erfchren produces extremely clean, normally liquid products. All of the over Π, rening factions

The fluids have an unusually high AFI density of iijenigstss -3, preferably above L and nncn more favorably above 5, one below M Ποω.) ό, preferably below; , Ll 'Πευ.'Ί lying -Jchwcfeinehalt and a below υ, 5 weight:'), preferably below L ,? ileui. ¹ ^ lienenrler. contains active ingredients. It is easy to see from the drawing that the invention is based on the invention and that it supplies liquid products from the cavity which are suitable for many purposes. The versatile oil product is particularly useful as a turbine fuel, while certain fractions are ice ienzin, iesel, Üüsenkraftstoff and rinl. einnen.

The advantages of the crfindunn arise from bus the Cetrochtunq next to it cigames.

Be is ρ ie 1 1

One from 33-eu. '/ J Illinois Hr. The coal and the recirculating slurry are passed through a dissolving zone as the first stage and then through a hydrocirculation zone as the second stage. The hphle uies a V rngrcße of LLL rninus on Tv / ler scale and had the following content, based on the dry matter: C: 6 * t, H: '*, 5, IY: I ₁ Ll, Ο: 12, 5 5: U, I , ash: 1 ^, 0 (data in 'em.%.). The solvent (recirculating oil) provided one
from a previous run.

Solvent (recirculating) represented an etSUi * C fraction which

Hydrogen was released into the first L at a rate of 283 m at 15.6 C per 159 l of the slurry ^; ₊ ufe introduced. The slurry remained with a Verueilzeit of ή, k hours in the first iitufe that at a temperature of FT6 ^ C under a D _r piece of 166.7 Hg / cm was kept pressure-atmospheres. The liquids ^r emic of the gases and solids uiurde completely because in the second tage passed, which had a fixed bed of hydrocracking catalyst, 6.6 Geu.% 19.2 winding souie Getu.% ÜJolfram with an alumina support contained. The second E ^ uffe was added

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809826/0857 BATH ORIGINAL

ο ?

a temperature of 35 ° C, below an orurk of 168.7 lin / cm above atmospheric pressure, and the humidity calculated from the supplied slurry was f;,? 5. The outgoing iJtrom was separated into transfer fluid (?. <U Γ +) and into the cibnel duct from the cavity. It is nrnEiben eichtifich 13Oi Lietrinbnstuiien fnlnenrie Erpgsnen:

I-Tcr! U! 'T lieui .;'. the 'raicenknh. ¹ ρ

VJl ? -. U - 371 39.7 371 - UGB IL, 2 Ufrß + (1 U, 2 unreacted coal 6, L ash 13.5 r-JH ,, K ₁ S, Hf 13.9

Ons normFileri.ieise fliissine '. rodukt, ie the C, up to and including Uhß - frpktinnnn had the following properties: /'.II: Π; Nitrogen: (.,? Reiii.%; Hrustoff: D, G9 Geuj.'o; Schefel: L, C3 Lieoj.i.

De ispiel

One of 25 wt% with one; nrngrrJfie from lLü-tninus on the Tyler-Sksln of Illinois rjr. Hollow and 75% by weight of hollow derived (2ί; ί »° +) slurry was sequentially passed through a dissolving zone as the first stage and a hydrocracking zone as the second stage as in Example 1. The transmission conditions of the first stage included a temperature of ** i * 6 C and 160.7! g / cm above atm. Hydrogen was added to the first stage at L'83 m at 15.6 C per 159 liters of slurry. The residence time of the slurry was 1.67 hours in the first stage. The entire mixture of fips, liquids and solids was then completely transferred to the second stage, in which a hydrocracking catalyst of the same composition as in Example 1 was used. The second call was initially made at a temperature of 1.6

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BAD ORlGINAt.

held under a pressure of / J ~ 0 Kq / cm. After 67 hours, the product quality dropped from 9.5 API to 1 AFI. The temperature was then raised to UUS C, the ^r ensity to 3.5 ° AFI rise, but dropped after a further 65 hours ü AFI. At a temperature of V * 6 ^D C, the catalyst had reached the end of its useful effect, when coking began to impede further operation.

The comparison of Examples 1 and 2 indicates how critical the maintenance is a low temperature in the hydrocracking stage of the process according to the invention.

For: Chevron Research Company

San Francisco // CaI., V.St.A.

Dr H. WoIff Lawyer

809826/0857

Claims (1)

ate η tans Ό avenge Γι j ι olilenvoril „.G ^ i ^ urinsverf.ihren iuit one through L.ischen formed by lcriletiilciidn with a solvent .ufcciil; i.aiiun ^ aas dissolved coal, characterized by ^ ie; eri.urencstufe: _0 v.'eifc ^ evenly loaen the coal in the solvent by uri / :. rriien aer ..ufschl.aaiüung to a between ~ t> - ^) and 48i: ilie ,, enae J Temperatur, whereby a Cxemisch formed // ira, a 3 ds solvent, which includes desires of coal and unlüciiche j '& otkorper, ■ j) & irikont- iibbriiig n of detiischs in a Keaktionszone with .KtüüGi'ütolf katalysi a una for the hydrogenating cleavage. 'Tor. I under hydrocracking conditions a Vem ^ er.itur unt ^ r ^L v27 ° ^> and O 9 B ? 6 / Π 8? 7 ORIGINAL BATHROOM c) derived aes has of uer, teuktionzone votes ^ tx Olis, whose normally liquid egg * .nteil an over -i lying .il- ^ ichbe. 2. / erfKiiron after ^ ns ^ ruch 'i, d-.aurch ^ denotes thatL The hollow in -Jegen ^ rt by the supplied hydrogen with A pressure above 3 ^ Lg / cni ^ above atm is solved. 5. Method according to the .nspxmch 1 oaer £ ', d'u. characterized by, d ^ ß the normally liquid part of the delivered Jtroms have an Al'I density greater than, an och-.vefelgen.lt of less ... Is ü, 1 CJe .v., j and a nitrogen part of less., Is o, 5 -few., a has. ^. / experience according to the ..ns ^ rumors 1, 1 or;>, characterized in that the normal C, 02 G-9, Vo and a nitrogen content of less than al3 J, 2 dev /. .j iut $. Method according to one of the preceding _; .ris ^ rdche, characterized in that the extension is heated to a temperature between 4-27 ° and 4-54 ° vJ and the hydrocrack at a temperature between 3 ^ 3 »3 ° and 399.9 ° ^ as well as under a -> -: ^ -? R?! I from 70 to 211 Kg / cm "" pressure lying above atm. 6. The method according to any one of the preceding claims, characterized in that the slurry in the presence of supplied hydrogen and in the absence of an externally supplied catalyst under a return? 0 ois 2 "l1 ig / cm ^ chlorine ¹ atm to an between 427 and 4- ^ 4 ^u 0 lying i 'tur er.vT.rc; t uird. BATH ORIGINAL 7. Process iiö, ch one of the preceding claims, characterized in that the weight ratio of solvent to coal is between ¹ yA and 0.5: 1 and the solvent contains a portion of the hydrocracking stream boiling ^{above 14-9 0 C,} 8. The method according to any one of the preceding claims, thereby characterized in that the iteaktionszone a fixed Has catalyst bed. 9. The method according to any one of the preceding in Proverbs, thereby characterized in that the catalyst used to be hydrogenated cleavage is a lethal group VIII and has a office crack carrier. 10. The method according to any one of the preceding claims, characterized by separating from the discharged stream of a normally gaseous fraction and insoluble solids and by recovering a normally liquid product stream with an API density of more than 5 "an ochulfelhalt less than 0.02 wt.?" And a nitrogen content below ₁ L Z ^wt., o. 11. The method according to claim 10, characterized in that at least the greater part of the insoluble solids is separated by gravity separation. 12. The method according to claim 11, characterized in that the gravity separation at a temperature between 92 $ 5 ° and V-Z? ° G and a pressure between 0 and 211 Kg / cm above atm is performed. 809826/0857